The need to reduce the surface humidity of the skin of fruit and vegetables produced on these when they undergo a washing process designed to remove dust, earth and similar after being picked and prior to being marketed is well known.
If not removed, the aforementioned humidity could affect their quality, accelerating rotting processes or the growth of fungi or similar on their surfaces.
In order to get rid of the damp on the surface of fruit and vegetables there is a wide variety of drying tunnels on the market, conventionally made from an enclosure which is crossed by these items in a counterflow direction and by a draught of hot air which, due to its temperature, is able to evaporate the humidity, carrying this outside the tunnel along with the draught of air.
The air blast, which is driven by means of blower or suction fans, is heated up by burners which work on fossil fuels such as diesel fuel, gas or coal, as well as by electrical resistance.
The use of fossil fuels causes unwanted residues to be incorporated in the air draught, which can transmit strange smells or flavours, this disadvantage being avoided in some drying tunnels by using heat exchangers or similar which increase the complexity of the ensemble.
The use of electrical resistance for heating the air draught allows the air temperature to be raised to the required level, not incorporating foreign bodies or gases in the products to be dried. Running these is nevertheless more costly than with the tunnels which have solid fuel burners.
In any event, the elimination of the damp in fruits and vegetables by means of hot air is not suitable due to the physical-chemical changes which take place inside said products, reducing their quality and thus, their final price.
Furthermore, the draught of hot air saturated with humidity which emerges from conventional drying tunnels is issued into the environment without any treatment, giving rise to unpleasant smells around the industries which incorporate drying tunnels in their fruit and vegetable drying chains.
The drying tunnels with treatment of the draughts of hot air saturated with humidity substantially increase the operative cost of the process, lowering the competitiveness of the companies which use these.
In view of the problematic existing in this field it would be desirable to have an improved drying tunnel applicable to fruit and vegetables whose operation were not based on the evaporation of water impregnating the surface of the products by hitting these with a blast of hot air, fully preserving their quality.
The applicant is not aware of the existence of any device which has the aforementioned advantage stated as being desirable for a device of this kind.